Study On Isolation And Characterization Of The Nonylphenol Degradation Strains

As an endocrine disruptor, NP (Nonylphenol, NP) is the maindegradation product of nonylphenol ethoxylates (NPEOs) and the toxicity,estrogenic activity, bioaccumulation of which have been widely confirmed.Large amount of domestic and foreign studies have proved that NP existedin various environmental media in different levels and posed a potentialthreat to human health and ecological security. How to decrease the dangerto the environment and the human body caused by NP pollution has drawngreat attention to many researchers.In this study, we tried to isolate effective strains that can degrade NPand minimize NP's biological toxicity and estrogenic activity, whichprovides technical assurance on improving and remediation of NP pollution.Two strains used NP as sole carbon source were obtained through thescreening, enrichment, separation and purification of strains in differentkinds of soil and sludge samples, and named N1 and N2 respectively.Further study has been done on the NP degradation characteristics,influencing factors and degradation kinetics model of strain N2. Finally, theNP degradating pathway of strain N2 was concluded.Results showed that: (1) Strains N1 and N2 were related to Achromobacter sp. and Serratiasp., respectively. Using the NP as the sole carbon source, both strains coulddegrade NP in different degrees after 7 days .(2) When the temperature is 30℃and NP concentration was less than100 mg·L^-1, the NP degradation caused by strain N2 accorded withfirst-order kinetic model. The increasing of NP concentration in solutioncould significantly inhibit the degradation of NP, and the growth of strainsand the degradation of NP basically were coincidence with theHaldane-Andrews models on the whole.(3)According to the testing results of the intermediate products andrelated literatures, it could be concluded that the NP was degraded by thestrains N2 through following processes. Firstly the alkyl chain was shortenand form series of short-chain alkyl phenols, then hydroquinone wasproduced, finally the benzene was damaged and the cycle of TCA began tostart.(4)Rotation speed, pH, strain inoculation, nitrogen sources, coexistingsubstrate and trace elements all had a certain impact on the degradation ofNP. The most effective degradation of NP can be achieved when pH is 6.5 ⁷.0, rotation speed is 100 150rpm, inoculum is 1%. It was proved that theammonium can be used more efficiently by the strains than organic nitrogenand nitrate. Coexisting substrate could improve the growth of strain N2, buthad no significant improvement on the degradation of NP. Trace elements inthe solution also played an important role in degradation of NP, Fe²⁺ andMg²⁺ could promote the degradation of NP significantly, while Cu²⁺ inhibited the degradation of the NP greatly.(5)Surfactant and solubilizer have a certain impact on the degradationof NP. In order to reduce the inhibition of low solubility, the researchprepared the NP emulsion by using the ethanol/NP stock solution to improvethe solubility of NP and increase the degradation efficiency of NP. Additionof Surfactant SDS and CTAB can both inhibit the degradation of NP. Underthe concentration of 3.6CMC and 0.53CMC, respectively, the addition ofTween 80 and Triton X-100 could improve the degradation of NP in certaindegrees.Through this study, two effective strains and the information about howStrain N2 degraded the NP were obtained. It provided the technical supportto the treatment and restoration of NP pollution, and had importantenvironmental and social meaning.